Process of manufacturing a substitute for leather.



AUGUST MEIER, OF SCHMARGENDORF,

NEAR BERLIN, AND HERMANN HALL, OF KARLS- HORST, NEAR BERLIN, GERMANY, ASSIGNORS TO GESELLSCHAFT FUR VERWER- TUNG CHEMISCHER PRODUKTS M.

B. H., OF BERLIN, GERMANY.

PROCESS OF MANUFACTURING A SUBSTITUTE FOR LEATHER.

N 0 Drawing.

To all whom it may concern:

Be it known that we, AUGUsT MEIER and I'IERMANN RALL, both citizens of the Empire of Germany, and residents, respectively, of Schmargendorf, near Berlin, and of Karlshorst, near Berlin, Germany, have invented certain new and useful Improvements in Processes of Manufacturing a Substitute for Leather, of which the following is a speci fication.

The object of the present invention is a process of manufacturing a substitute for leather, in which albumins are employed as raw material.

If albumins are tanned with vegetable tanning substances the products thereby obtained are soft, partly adhesive and grainable with ditficulty; furthermore they are not sufliciently proof against mechanical abrasion.

Again if "the albumins are tanned with mineral salts, hard and brittle, and badly grainable products are obtained.

It is an object of the present invention to overcome the disadvantages attending the above processes.

A very superior substitute for leather can be obtained by the use of the disclosed combined tanning method. For the obtaining of such products only the top layer of the albumins need be hardened with mineral tanning substances, 6. g., chromium, iron, aluminium, cerium-salts or the like, the remaining parts being tanned with vegetable, 2'. e., organic tanning agents as chestnut bark, sumach, myrobalan or formalin.

Preferably should not be very concentrated. Thus, if a chrome salt solution is used, the same should contain not more than 2 per cent. chromium oxid (H 0 Furthermore the strongly diluted tanning baths should be preferably thoroughly cooled. A temperature of about 59 F. will be found to give excellent results which is contrary to what one would obtain when tanning animal hides, in which case temperatures of 77 to 86 F. have to be kept.

If for example the first tanning is done with a solution of chromic oxid of, say, 0.1 per cent, an action of half an hour will quite suiiice. The use of very concentrated Specification of Letters Patent.

the mineral tanning bath Patented Dec. 10, 1918.

Application filed February 12, 1915. Serial No. 7,915.

mineral tanning solutions is to be avoided since With a solution of chromic oxid of 2 per cent, andan action lasting only 5 minutes the layers of albumins become too hard and too brittle. The time required for the first tanning operation should depend on the nature of the chromic salts employed and the proper time is to be ascertained for each salt individually by experiments. The

upon it is later completely tanned by means of vegetable extracts for example. The finishing of the leather substitute is then proceeded with according to any one of the known processes.

The vegetable tanning may, however, be done first, whereupon the surface of the albumins tanned by the vegetable process is subsequently hardened by a solution of mineral salts as already described. The products obtained in this manner are serviceable, but they are generally not so good as those prepared according to the previously described method.

The albumins referred to above in connection with the new process are to be understood as comprising bacteria, yeast-albumin, albumin, glue, mixtures of these substances and the like.

The organic tanning medium which necessarily includes the vegetable media is to be understood as also including formalin. Thus one can layers of albumins hardened by the mineral tanning medium are brought into contactwith a weak formalin bath. Should the proceed in such a manner that thc tanning be done with stronger solutions of formalin then the material may lose the soft feel common to natural leather and acquire ,pending on the Under certain circumstances the time period may rise to several (twelve) hours. Thereupon a rinsing with water takes place, as before, prior to the immersion. into the formalin bath. It is then treated with smoothing mediums and finally it is grained in a very hot state under pressure. As against a vegetable tanning extract formalin has the advantage that the products obtained are of a light color. Vegetable extract always produces a light brown color; moreover it is to be borne in mind that vegetable extract precludes the use of a number of colors, (for instance, iron colors, since t-annates of iron are-formed).

Treatment with formalin can also precede the tanning in the mineral tanning bath. Moreover the formalin may be added to the vegetable tanning bath and used as the vegetable extract tanning bath is used.

A modification of the processes above described is obtained by adding to the original solutions of albumins, vegetable tanning substances or formalin, smoothing means or the like, or mixtures of such substances. Such masses are spread upon well known carriers, for example, tissues, and after congealing as already mentioned, they are hardened in the mineral tanning bath. In this operation any excess of tanning materials in the albumins must be avoided, as by adding too much tanning substances the albumins become overtanned and therefore brittle. This latter process requires, in general, an addition of smoothing means to the mineral tanning bath, as otherwise the added materials are apt to be washed out ,of the product to be tanned.

Another modification of the process consists in the application of the tanning solutions, by spraying, squirting or spreading the solutions upon the congealed albumins on the carriers by means of a sponge, a brush or the like, either by hand or by machinery, so that the tanning solutions may penetrate the product.

In this manner both the hardening with mineral tanning extract and the final tanning with vegetable tanning substances or formalin can be carried out. The last mentioned tanning substances may also be incorporated with the albumins so that only the mineral tanning substances are to be superficially spread.

11 employing formalin the treatment of the product can also be carried out by means of subjecting the product to the vaexpressions,

por of formalin. By proceeding in this way a saving of the smoothing means will result and a considerable simplification of the whole process becomes possible by the omission of the baths, besides it now becomes possible to perform all the operations at normal indoor temperature, for even the hardening process by mineral tanning no longer requires the observance of low temperatures. With this treatment the hides swell much less than with the above mentioned process, in which the baths are employed. Thus it is now possible to perform the graining of the superficially hardened layers of albumins between the times of application of the mineral and the vegetable tanning substances or-formalin.

The manufacture of a leather substitute may also be accomplishedby having the spread material first hardened on the surface by mineral tanning substances,- and then conducting the final tanning by vegetable substances, formalin ormixtures of the two from the back of the carrier. For example in the manufacture of substitutes for patent leather the hardened lamina is varnished, whereupon graining is done thereon and finally the vegetable tanning substances or the formalin is squirted on the back. I

As examples of smoothing means may be mentioned: glycerin, soap, molasses, hygroscopic salts, oils and the like, which are to be added to the albumins in the beginning of the process and if desired thereafter with ground leather, factis, oil, colors and the like. The smoothing means may also be added to the baths, should such be employed.

It is possible that the effect of the mineral tan is to produce a fairly stable surface tan which the subsequent vegetable tanning does not affect and hence merely the remainder or unta'nned portion of the tannable material is affected by the vegetable tan; or it may be that the mineral tanned surface receives an additional tanning when the vegetable tan is applied.

When the vegetable tan is first, applied and then the mineral tan, it is possible that the mineral tan either causes anadditional tanning of the already vegetable tanned material or displaces the vegetable tan so that the surface is, strictly speaking, only mineral tanned.

When we speak in our claims of body tanning and surface tanning, or use similar.

we do not desire it to be interpreted that the surface may not also be vegetable tanned.

caster-oil, wood- When we speak in our claims of formalin rubbing in the agents by suitable means;

and we do not mean to imply that the tanning agent consists of only one tanning agent.

\Ve claim:

1. The improvement in the art of producing a substitute for leather which comprises the steps of treating a tannable material with one kind of tanning agent and then with a different kind of tanning agent.

2. The improvement in the art of producing a substitute for leather Whichcomprises the steps of treating a tannable material with a mineral tanning agent, and then with another tanning agent.

3. The improvement in the art of producing a substitute for leather which comprises the steps of treating a tannable material with a mineral tanning agent, and then with an organic tanning agent.

r. The improvement in the art of producing a substitute for leather which comprises the steps of treating a tannable material with a solution containing chromium oxid and then with an organic tanning agent.

The improvement in the art of producing a substitute for leather which comprises the steps of treating a tannable material with a solution containing not more than two per cent. chromium oXid and then with an organic tanning agent.

6. The improvement in the art of producing a substitute for leather which comprises the steps of treating an albuminous material with one kind of tanning agent and then with another kind of tanning agent.

7. The improvement in the art of producing a substitute for leather which comprises the steps of treating an albuminous material with a mineral tanning agentand then with an organic tanning agent.

8. The improvement in the art of producing a substitute for leather which comprises the steps of treating an albuminous material with a mineral tanning agent and then with a vegetable tanning agent.

9. The improvement in the art of producing a substitute for leather which comprises the steps of treating an albuminous material with a mineral tanning agent, then with a vegetable tanning agent and finally with formalin.

10. The improvement in the art of producing a substitute for leather which comprises the steps of treating an albuminous material With a mineral tanning agent, and then with formalin.

11. A substitute for leather an organically tanned body and tanned surface.

comprising a mineral AUGUST MEIER. HERMAN N RALL.

Witnesses W OLDEMAR HAUPT, HENRY HASPER. 

